Final answer:
The claim that magnetic grains in basalt align with Earth's magnetic field upon solidification is true, reflecting the historical geomagnetic field orientation and solidifying the concept that Earth's magnetic field reverses periodically.
Step-by-step explanation:
The statement that the dipoles of small magnetic grains in basalt align with the magnetic field of the Earth upon solidification is TRUE. Essential Knowledge 2.D.3 supports this fact by stating that a magnetic dipole will tend to align with the magnetic field vector that it is placed within. This principle is observed in volcanic rocks such as basalt, where iron-rich minerals within the molten rock function as tiny dipoles. As the rock solidifies, these minerals freeze in place, aligned with Earth's magnetic field at the time of their solidification. This phenomenon is not only a testament to the existing magnetic field during rock formation but also serves as a historical record of Earth's magnetic field reversals, giving insight into the geomagnetic history.
Additionally, the presence of these aligned magnetic grains in volcanic rocks found at the mid-Atlantic ridge points to the historical geomagnetic field orientation. This implies that the Earth's magnetic field has reversed multiple times throughout its history, a fact that is further evidenced by the Earth's magnetic field flipping direction approximately every 200,000 years.
Last but not least, it is also true that if a magnet shatters, each piece will retain its own north and south poles, according to the Big Idea 3 and Enduring Understanding 3.C.